var strs = "";

function OnClick(obj) {
    var str = obj;
    var numInput_1 = document.getElementById("numInput_1");
    var numInput_2 = document.getElementById("numInput_2");


    if (str == "=") {
        str = numInput_2.value;
        strs = eval(str);
        numInput_1.value = strs;
    } else if (str == "c") {
        numInput_1.value = "";
        numInput_2.value = "";
        str = "";
        strs = "";
    } else if (str == "+" || str == "-" || str == "*" || str == "/") {
        numInput_2.value += str;
        strs = numInput_2.value
    } else {
        numInput_2.value += str;
        strs = numInput_2.value
    }
}